Substrate or panel with releasable core

ABSTRACT

Generally discussed herein are systems and apparatuses that can include a base with one or more recesses therein. The disclosure also includes techniques of making and using the systems and apparatuses. According to an example a technique of making a releasable core panel can include providing a releasable core, the releasable core including a first conductive foil integrally coupled with a base at a first side of the base and a first side of the conductive foil, the first conductive foil situated in a first recess in the first side of the base. The technique can include releasably coupling a second conductive foil to a second side of the first conductive foil through a temporary adhesive layer integrally coupled to a first side of the second conductive foil, the second side of the first conductive foil opposite the first side of the first conductive foil.

TECHNICAL FIELD

Examples generally relate to substrate architectures that can include areleasable or reusable core.

TECHNICAL BACKGROUND

Substrate manufacturing technology can include the use of panels to helpincrease the number of dies that can be manufactured at a given time.Substrate manufacturing can be inefficient or wasteful and costprohibitive. Such problems can be prevalent when building substratesusing one or more panels.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 shows an example of a core panel.

FIG. 2 shows the example core panel of FIG. 1 after material has beenremoved from the core panel.

FIG. 3 shows an example of another core panel.

FIG. 4 shows the core panel of FIG. 3 prior to coupling a conductivefoil to a base.

FIG. 5 shows an example of the panel of FIG. 3 after substrates havebeen formed on the top and bottom surfaces of the core panel.

FIG. 6 shows an example of the panel of FIG. 6 after substrates andconductive foils have been released from the core panel.

FIG. 7 shows the conductive foil and substrate after a temporaryadhesive layer has been removed from a conductive foil.

FIG. 8 shows an example of a technique for making a core panel.

FIG. 9 shows an example of a computer system.

DESCRIPTION OF EMBODIMENTS

Examples in this disclosure relate to substrates or panels, such aspanels that can include coreless substrates, and methods of making andusing the same. Examples also relate to systems that can include one ormore of the substrates or panels.

FIG. 1 shows a core panel 100. The core panel 100 can be substantiallysimilar to a core panel currently received at a Substrate PackagingTechnology Development (SPTD) factory. The core panel can include agenerally rectangular base 102, one or more inner conductive foils 104Aor 104B, one or more temporary adhesive layers 106A or 106B, or one ormore outer conductive foils 108A or 108B. One or more Dry Film Resist(DFR) layers 110A or 110B can be situated on the core panel 100, such asat the SPTD factory, such as shown in FIG. 1.

A panel, such as the core panel 100, can undergo processing before asubstrate is formed on the panel, such as at a SPTD factory. The corepanel 100 can undergo an etching process, such as to produce the corepanel 200 shown in FIG. 2. The etching process can expose the outerconductive foil 108A-B, at least partially remove the DFR layers 110A-B,or remove a portion of the inner conductive foils 104A-B, temporaryadhesive layers 106A-B, or outer conductive foils 108A-B. The etchingprocess can cause a width, indicated by the line 212, to be unsuitablefor building a substrate thereon in a substrate building process. Thewidth, indicated by the line 214, can be the area of the core panel 200that is suitable for building a substrate thereon in the substratebuilding process. The substrate can be built on the outer conductivefoil 108A-B.

A substrate built on the outer conductive foil 108A-B can be releasedfrom (e.g., pulled off of or otherwise removed from) the panel, such asat the temporary adhesive layer 106A-B. The outer conductive foil 108A-Bcan be separated from the core panel 200. Since the temporary adhesivelayer 106A-B and the outer conductive foils 108A-B typically come inpanels, the temporary adhesive layer generally cannot be reapplied tothe inner conductive foil 104A-B. This is because the inner conductivefoil 104A-B has diminished in surface area, such as at or near the widthindicated by line 212, so as to prohibit the application of a temporaryadhesive layer 106A-B panel to the inner conductive foil 104A panel.Thus, the panel that includes the base 102 and the inner conductivefoils 104A-B is typically discarded and a new panel is brought in forprocessing.

The temporary adhesive layers 106A-B can be made of methyl ethyl ketoneand toluene solvents with polydimethyl siloxane and bisphenol A basedepoxy. Temporary adhesive layers 106A-B made from these materials cansuffer from phase separation between the epoxy and silicone over time.Heat can cause blisters to form in temporary adhesive layers 106A-B madefrom these materials. The adhesive strength of such temporary adhesivelayers 106A-B can degrade over time. Temporary adhesive layers made ofthese materials can have poor line yields, such as in a SPTD factory.

The outer conductive foil 108A can be a micro thin copper panel. Thispanel can be costly, such as compared to a thicker copper panel. Thisouter conductive foil 108A can typically be about 5 micrometers thick.

FIG. 3 shows an example of a core panel 300. When the core panel 300 isreceived a SPTD factory, one or more substrates can be formed on thecore panel 300 (see FIG. 6, for example), such as without performing anyprocessing on the core panel 300 before forming the substrates. Suchprocessing is described, with regard to FIG. 2, for example.

The core panel 300 can include a base 302A, one or more inner conductivefoils 304A or 304B, one or more temporary adhesive layers 306A or 306B,or one or more outer conductive foils 308A or 308B.

The base 302A can include one or more recesses 316A or 316B formedtherein. The recess 316A-B can include a depth, such as indicated bylines 318A and 318B, respectively and a width, such as indicated bylines 320A and 320B, respectively. The recess 316A-B can be configuredto accommodate a substantial portion or all of the temporary adhesivelayer 306A-B, such as to allow the temporary adhesive layer 306A-B toreside at least partially in the recess 316A-B and also make contactwith the inner conductive foil 304A-B, such as to form a releasable(e.g., adhesive) coupling between the inner conductive foil 304A-B andthe temporary adhesive layer 306A-B. The base 302A can be generallyshaped as a sideways capital “I”, such as in a vertical cross-section ofthe base 302A, such as shown in FIG. 3. The base 302A can be made of anepoxy resin, glass cloth, other base material, or a combination thereof.The base 302A can be made of a cured prepreg.

The inner conductive foil 304A-B can be situated at least partiallywithin the recess 316A-B. The inner conductive foil 304A-B can be madeof copper, aluminum, or other conductive material. The inner conductivefoil 304A-B can include a height (e.g., a dimension substantiallyparallel to the line 318A-B) of about one micrometer to greater than amillimeter. In one or more embodiments, the inner conductive foil 304A-Bcan be between about five and eighteen micrometers in height.

The temporary adhesive layer 306A-B can releasably or mechanicallycouple the inner conductive foil 304A-B to the outer conductive foil308A-B, respectively. As used herein releasably coupling means to couplesuch that a mechanical coupling through the temporary adhesive layer306A-B can be broken without requiring excessive force or damaging theitems mechanically coupled through the temporary adhesive layer 306A-B.The temporary adhesive layer 306A-B can be released from an item byexerting a relatively small amount of force, such as about five Newtonsper meter to about one hundred Newtons per meter.

The temporary adhesive layer 306A-B can be made of one or more epoxysilicone copolymers or blends of polymers, silicone, or epoxy. Differentblends can be used to make temporary adhesive layers 306A-B with varyingmechanical properties, such as depending on the volume weight percent ofpolymer, silicone, or epoxy used. The mechanical properties can includehardness, elasticity, stickiness, or other mechanical property.

The temporary adhesive layer 306A-B can be made of an epoxy and siliconeblend. For example, siloxane and epoxy resin can be blended togetherwith a carboxylic acid anhydride hardener, such as to produce a stableor well-blended temporary adhesive layer 306A-B. This blend can be usedas an adhesive by controlling the siloxane to epoxy resin ratio. Byincreasing the proportion of siloxane, a temporary adhesive layer 306A-Bwith a reduced elastic modulus can be produced.

The temporary adhesive layer 306A-B can be made of a blend ofco-polymer, epoxy, or silicone. A co-polymer of siloxane and epoxy canbe produced and mixed with an epoxy resin. Polysiloxane can have anepoxide group on a side chain thereof and can be synthesized frommethylhydrosiloxane, epoxy resin.

The outer conductive foils 308A-B can be situated on a surface of thebase 302A. The outer conductive foil 308A-B can be integrally coupledwith or attached to the temporary adhesive layer 306A, such that whenthe outer conductive foil 308A-B is decoupled from the core panel 300,the temporary adhesive layer 306A-B is also decoupled from the corepanel 300, such as by breaking a releasable coupling between thetemporary adhesive layer 306A-B and the inner conductive foil 304A-B. Anintegral or other mechanical coupling between the outer conductive foil308A-B and the temporary adhesive layer 306A-B can be a strongercoupling than a releasable coupling between the temporary adhesive layer306A-B and the inner conductive foil 304A-B.

The outer conductive foil 308A-B can be made of copper, aluminum, orother conductive material. The inner conductive foil 304A-B can includea height (e.g., a dimension substantially parallel to the line 318A) ofabout one micrometer to greater than one millimeter. In one or moreembodiments, the outer conductive foil 308A-B can be between about fiveand about eighteen micrometers in height.

FIG. 4 shows the core panel 300 of FIG. 3 prior to releasably couplingthe outer conductive foil 308A-B to the base 302A. The temporaryadhesive layers 306A-B can be pressed (e.g., hot pressed, baked withpressure, or laminated) into the inner conductive foils 304A-B. Suchpressing can form a releasable coupling between the inner conductivefoil 304A-B and the outer conductive foil 308A-B, such as shown in FIG.3. The base 302A and the inner conductive foil 304A-B can be reused byreleasably uncoupling (e.g., pulling) the inner conductive foil 304A-Bfrom the outer conductive foil 308A-B. More details regarding reusingthe base 302A and inner conductive foil 304A-B panel are explained withregard to FIG. 6.

FIG. 5 shows the core panel 300 of FIG. 3 with one or more substrates524A or 524B formed on a top surface 526 or a bottom surface 528 of thecore panel 300, respectively. The substrate 524A-B can be formed on theouter conductive foil 308A-B, respectively. The substrate 524A-B can bea Bumpless BuildUp Layer (BBUL) substrate, a Flip Chip substrate, orother type of substrate. The substrate 524A-B can be a corelesssubstrate, such as a substrate that does not include a die situated inthe substrate.

FIG. 6 shows the core panel 300 of FIG. 5 with the outer conductive foil308A-B releasably decoupled from the inner conductive foil 304A-B.Releasably decoupling the inner conductive foil 304A-B from the outerconductive foil 308A-B can include chemical etching or pulling so as toremove the outer conductive foil 308A-B from the core panel 300. Thepanel including the base 302A or the inner conductive foil 304A-B (inembodiments that include the inner conductive foil 304A-B, see FIG. 4for an example of an embodiment that does not include the innerconductive foil 304A-B) can be reused. Reusing can include hot pressingor otherwise releasably coupling another outer conductive foil 308A-B ortemporary adhesive layer 306A-B to the base 302A panel, such as a basepanel with or without the inner conductive foil 304A-B.

FIG. 7 shows the substrate 524A and the outer conductive foil 308A ofFIG. 6 with the temporary adhesive layer 306A removed from the outerconductive foil 308A. The temporary adhesive layer 306A can be removedby wet blasting, mechanical etching, chemical etching, laser ablation, acombination thereof, or other process of removing the temporary adhesivelayer 306A.

By including a base 302A-B panel in a substrate manufacturing process,costs can be reduced, such as by allowing the base 302A-B panel (e.g.,with or without the inner conductive foil 304A-B) to be reused.Including the base 302A-B in the process of making a substrate can alsosimplify the manufacturing process, such as by removing base panelbuildup steps or one or more etch steps from the substrate manufacturingprocess. By making the inner conductive foil 304A-B or the outerconductive foil 308A-B thicker than five micrometers, the cost can bereduced. By including base 302A-B the active area (e.g., the area onwhich substrates can be formed) can be increased compared to a processthat includes an etch step, such as described with regard to FIGS. 1 and2.

FIG. 8 shows an example of a technique 800 for making a core panel, suchas a core panel discussed herein. At 802, a releasable core (e.g., abase, such as base similar to 302A-B or one or more inner conductivefoils 304A-B) can be provided. The releasable core can include a firstconductive foil 304A integrally coupled with a base 302A at a first sideof the base 302A and a first side of the conductive foil 304A, the firstconductive foil 304A situated in a first recess 316A in the first sideof the base 302A. At 804, a second conductive foil 308A can bereleasably coupled to a second side of the first conductive foil 304Athrough a temporary adhesive layer 306A integrally coupled to a firstside of the second conductive foil 308A. The second side of the firstconductive foil 304A opposite the first side of the first conductivefoil 304A. Releasably coupling the first temporary adhesive layer 306Acan include hot pressing the first temporary adhesive layer 306A intothe first conductive foil 304A.

The technique 800 can include forming a first substrate 524A on a secondside of the second conductive foil 308A. The first substrate 524A can bea BBUL substrate. The first substrate 524A can be a coreless substrate.The second side of the second conductive foil 308A can be opposite thefirst side of the second conductive foil 308A. The releasable core caninclude a third conductive foil 304B integrally coupled with the base302A at a second side of the base 302A and a first side of the thirdconductive foil 304B. The third conductive foil 304B can be situated ina second recess 316B in a second side of the base 302A, the second sideof the base 302A opposite the first side of the base 302A. The technique800 can further include releasably coupling a fourth conductive foil308B to a second side of the third conductive foil 304B through a secondtemporary adhesive layer 306B integrally coupled to a first side of thefourth conductive foil 308B, the second side of the third conductivefoil 308B opposite the first side of the third conductive foil 308B.

The technique 800 can include forming a second substrate 524B on asecond side of the fourth conductive foil 308B. The second substrate canbe a BBUL substrate. The second substrate 524B can be a corelesssubstrate. The second side of the fourth conductive foil 308B can beopposite the first side of the fourth conductive foil 308B. Thetechnique 800 can include releasing (e.g., pulling or otherwisedecoupling) the second conductive foil 308A and the fourth conductivefoil 308B from the releasable core. The technique 800 can includereusing the releasable core by attaching another conductive foil to thefirst conductive foil of the releasable core. The technique 800 caninclude removing the first temporary adhesive layer 306A from the secondconductive foil 308A.

FIG. 9 is a block diagram illustrating an example computer system 900machine which can include a reusable core panel discussed herein.Computer system 900 can be a computing device. In an example, themachine can operate as a standalone device or can be connected (e.g.,via a cellular network) to other machines. In a networked deployment,the machine can operate in the capacity of either a server or a clientmachine in server-client network environments, or it can act as a peermachine in peer-to-peer (or distributed) network environments. Further,while only a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines that individually orjointly execute a set (or multiple sets) of instructions to perform anyone or more of the methodologies discussed herein.

Example computer system 900 can include a processor 902 (e.g., a CentralProcessing Unit (CPU), a Graphics Processing Unit (GPU) or both), a mainmemory 904 and a static memory 906, which communicate with each othervia an interconnect 908 (e.g., a link, a bus, etc.). The computer system900 can further include a video display unit 910, an alphanumeric inputdevice 912 (e.g., a keyboard), and a User Interface (UI) navigationdevice 914 (e.g., a mouse). In an example, the video display unit 910,input device 912 and UI navigation device 914 are a touch screendisplay. The computer system 900 can additionally include a storagedevice 916 (e.g., a drive unit), a signal generation device 918 (e.g., aspeaker), an output controller 932, a power management controller 934,and a network interface device 920 (which can include or operablycommunicate with one or more antennas 930, transceivers, or otherwireless communications hardware), and one or more sensors 928, such asa GPS sensor, compass, location sensor, accelerometer, or other sensor.The antennas 930 can be coupled to a network 926.

Examples and Notes

The present subject matter may be described by way of several examples.

Example 1 can include or use subject matter (such as an apparatus, amethod, a means for performing acts, or a device readable memoryincluding instructions that, when performed by the device, can cause thedevice to perform acts), such as can include or use providing areleasable core, the releasable core including a first conductive foilintegrally coupled with a base at a first side of the base and a firstside of the conductive foil, the first conductive foil situated in afirst recess in the first side of the base, and releasably coupling asecond conductive foil to a second side of the first conductive foilthrough a temporary adhesive layer integrally coupled to a first side ofthe second conductive foil, the second side of the first conductive foilopposite the first side of the first conductive foil.

Example 2 can include or use, or can optionally be combined with thesubject matter of Example 1, to include or use forming a first substrateon a second side of the second conductive foil, the second side of thesecond conductive foil opposite the first side of the second conductivefoil.

Example 3 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-2, to include or usewherein the releasable core further includes a third conductive foilintegrally coupled with the base at a second side of the base and afirst side of the third conductive foil, the third conductive foilsituated in a second recess in a second side of the base, the secondside of the base opposite the first side of the base. Example 3 canoptionally include or use releasably coupling a fourth conductive foilto a second side of the third conductive foil through a second temporaryadhesive layer integrally coupled to a first side of the fourthconductive foil, the second side of the third conductive foil oppositethe first side of the third conductive foil.

Example 4 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-3, to include or useforming a second substrate on a second side of the fourth conductivefoil, the second side of the fourth conductive foil opposite the firstside of the fourth conductive foil.

Example 5 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-4, to include or usewherein forming the first substrate includes forming a first bumplessbuildup layer substrate and forming the second substrate includesforming a second bumpless buildup layer substrate.

Example 6 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-5, to include or usereleasing the second conductive foil and the fourth conductive foilsfrom the releasable core.

Example 7 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-6, to include or usereusing the releasable core by attaching another conductive foil to thefirst conductive foil of the releasable core.

Example 8 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-7, to include or usewherein releasably coupling the first temporary adhesive layer includeshot pressing the first temporary adhesive layer into the firstconductive foil.

Example 9 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-8, to include or useremoving the first temporary adhesive layer from the second conductivefoil.

Example 10 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-9, to include or usewherein forming the first substrate includes forming a first corelesssubstrate and forming the second substrate includes forming a secondcoreless substrate.

Example 11 can include or use, or can be optionally be combined with thesubject matter of at least one of Examples 1-10, to include subjectmatter (such as an apparatus, a method, a means for performing acts, ora device readable memory including instructions that, when performed bythe device, can cause the device to perform acts), such as can includeor use a temporary adhesive layer including a first width, a firstconductive foil integrally coupled with a first side of the temporaryadhesive layer, the first conductive foil including a second width, thesecond width greater than the first width, a second conductive foilreleasably coupled to a second side of the temporary adhesive layer at afirst side of the second conductive foil, the second side of thetemporary adhesive layer opposite the first side of the temporaryadhesive layer, and a base integrally coupled to a second side of thesecond conductive foil, the second side of the conductive foil oppositethe first side of the second conductive foil.

Example 12 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-11, to include or usewherein the second conductive foil is situated in a recess in a firstside of the base and the temporary adhesive layer is situated, at leastpartially, in the recess.

Example 13 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-12, to include or usewherein the temporary adhesive layer is a first temporary adhesive layerand wherein the second conductive foil is situated on and integrallycoupled to the base at a first side of the base. Example 13 canoptionally include or use wherein the substrate further included a thirdconductive foil situated on and integrally coupled to a second side ofthe base at a first side of the third conductive foil, the second sideof the base opposite the first side of the base, and a second temporaryadhesive layer releasably coupled to a second side of the thirdconductive foil at a first side of the second temporary adhesive layer.

Example 14 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-13, to include or use afourth conductive foil situated on an integrally coupled with a secondside of the second temporary adhesive layer, the second side of thesecond temporary adhesive layer opposite the first side of the secondtemporary adhesive layer.

Example 15 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-14, to include or usewherein the recess is a first recess, wherein the second temporaryadhesive layer is situated in a second recess in a second side of thebase, wherein the third conductive foil is situated, at least partially,in the second recess, and wherein the second side of the base isopposite the first side of the base.

Example 16 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-15, to include or usewherein the first and second temporary adhesive layers are selected fromthe group including (1) epoxy and silicone mixed with a hardener and (2)a co-polymer of epoxy and silicone mixed with an epoxy resin.

Example 17 can include or use, or can be optionally be combined with thesubject matter of at least one of Examples 1-16, to include subjectmatter (such as an apparatus, a method, a means for performing acts, ora device readable memory including instructions that, when performed bythe device, can cause the device to perform acts), such as can includeor use a base with a first recess in a first side of the base and asecond recess in a second side of the base, the first side of the baseopposite the second side of the base, a first conductive foil situatedin the first recess, and a second conductive foil situated in the secondrecess.

Example 18 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-17, to include or usewherein the first and second recesses and the first and secondconductive foils are generally rectangular in shape and wherein thefirst and second recesses extend beyond the first and second conductivefoils, respectively.

Example 19 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-18, to include or usewherein the first and second conductive foils are copper foils.

Example 20 can include or use, or can optionally be combined with thesubject matter of at least one of Examples 1-19, to include or usewherein the base is made of glass cloth and epoxy.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which methods,apparatuses, and systems discussed herein can be practiced. Theseembodiments are also referred to herein as “examples.” Such examples caninclude elements in addition to those shown or described. However, thepresent inventors also contemplate examples in which only those elementsshown or described are provided. Moreover, the present inventors alsocontemplate examples using any combination or permutation of thoseelements shown or described (or one or more aspects thereof), eitherwith respect to a particular example (or one or more aspects thereof),or with respect to other examples (or one or more aspects thereof) shownor described herein.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

As used herein, a “-” (dash) used when referring to a reference numbermeans “or”, in the non-exclusive sense discussed in the previousparagraph, of all elements within the range indicated by the dash. Forexample, 103A-B means a nonexclusive “or” of the elements in the range{103A, 103B}, such that 103A-103B includes “103A but not 103B”, “103Bbut not 103A”, and “103A and 103B”.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription as examples or embodiments, with each claim standing on itsown as a separate embodiment, and it is contemplated that suchembodiments can be combined with each other in various combinations orpermutations. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A method of making a core panel comprising:providing a releasable core, the releasable core comprising a firstconductive foil integrally coupled with a base at a first side of thebase and a first side of the conductive foil, the first conductive foilsituated in a first recess in the first side of the base; and releasablycoupling a second conductive foil to a second side of the firstconductive foil through a temporary adhesive layer integrally coupled toa first side of the second conductive foil, the second side of the firstconductive foil opposite the first side of the first conductive foil. 2.The method of claim 1, further comprising: forming a first substrate ona second side of the second conductive foil, the second side of thesecond conductive foil opposite the first side of the second conductivefoil.
 3. The method of claim 2, wherein the releasable core furthercomprises: a third conductive foil integrally coupled with the base at asecond side of the base and a first side of the third conductive foil,the third conductive foil situated in a second recess in a second sideof the base, the second side of the base opposite the first side of thebase; and the method further comprises: releasably coupling a fourthconductive foil to a second side of the third conductive foil through asecond temporary adhesive layer integrally coupled to a first side ofthe fourth conductive foil, the second side of the third conductive foilopposite the first side of the third conductive foil.
 4. The method ofclaim 3, wherein the method further comprises: forming a secondsubstrate on a second side of the fourth conductive foil, the secondside of the fourth conductive foil opposite the first side of the fourthconductive foil.
 5. The method of claim 4, wherein forming the firstsubstrate includes forming a first bumpless buildup layer substrate andforming the second substrate includes forming a second bumpless builduplayer substrate.
 6. The method of claim 5, further comprising releasingthe second conductive foil and the fourth conductive foils from thereleasable core.
 7. The method of claim 6, further comprising reusingthe releasable core by attaching another conductive foil to the firstconductive foil of the releasable core.
 8. The method of claim 7,wherein releasably coupling the first temporary adhesive layer includeshot pressing the first temporary adhesive layer into the firstconductive foil.
 9. The method of claim 8, further comprising removingthe first temporary adhesive layer from the second conductive foil. 10.The method of claim 9, wherein forming the first substrate includesforming a first coreless substrate and forming the second substrateincludes forming a second coreless substrate.
 11. An substratecomprising: a temporary adhesive layer including a first width; a firstconductive foil integrally coupled with a first side of the temporaryadhesive layer, the first conductive foil including a second width, thesecond width greater than the first width; a second conductive foilreleasably coupled to a second side of the temporary adhesive layer at afirst side of the second conductive foil, the second side of thetemporary adhesive layer opposite the first side of the temporaryadhesive layer; and a base integrally coupled to a second side of thesecond conductive foil, the second side of the conductive foil oppositethe first side of the second conductive foil.
 12. The substrate of claim11, wherein the second conductive foil is situated in a recess in afirst side of the base and the temporary adhesive layer is situated, atleast partially, in the recess.
 13. The substrate of claim 12, whereinthe temporary adhesive layer is a first temporary adhesive layer andwherein the second conductive foil is situated on and integrally coupledto the base at a first side of the base, and the substrate furthercomprises: a third conductive foil situated on and integrally coupled toa second side of the base at a first side of the third conductive foil,the second side of the base opposite the first side of the base; and asecond temporary adhesive layer releasably coupled to a second side ofthe third conductive foil at a first side of the second temporaryadhesive layer.
 14. The substrate of claim 13, further comprising afourth conductive foil situated on an integrally coupled with a secondside of the second temporary adhesive layer, the second side of thesecond temporary adhesive layer opposite the first side of the secondtemporary adhesive layer.
 15. The substrate of claim 14, wherein therecess is a first recess, wherein the second temporary adhesive layer issituated in a second recess in a second side of the base, wherein thethird conductive foil is situated, at least partially, in the secondrecess, and wherein the second side of the base is opposite the firstside of the base.
 16. The substrate of claim 15, wherein the first andsecond temporary adhesive layers are made of one selected from the groupcomprising (1) epoxy and silicone mixed with a hardener and (2) aco-polymer of epoxy and silicone mixed with an epoxy resin.
 17. Areusable, releasable core comprising: a base with a first recess in afirst side of the base and a second recess in a second side of the base,the first side of the base opposite the second side of the base; a firstconductive foil situated in the first recess; and a second conductivefoil situated in the second recess.
 18. The reusable, releasable core ofclaim 17, wherein the first and second recesses and the first and secondconductive foils are generally rectangular in shape and wherein thefirst and second recesses extend beyond the first and second conductivefoils, respectively.
 19. The reusable, releasable core of claim 18,wherein the first and second conductive foils are copper foils.
 20. Thereusable, releasable core of claim 19, wherein the base is made of glasscloth and epoxy.